This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Self-paced paradigms allow for optimal timing in individual patients, providing increased focus in normal subjects and variability in stimulus duration for cognitively impaired patients. To validate several self-paced n-back paradigms, fourteen subjects performed four variations of the working memory task using visually-presented letters as stimuli. Several areas in the frontal lobe, the anterior cingulate, and a parietal network were consistently activated. No significant differences were found in the four variations: identity of black letters, location of black letters, color of colored letters and identity of colored letters. The results agree well with meta-analysis and other published results, giving confidence that a self-paced n-back paradigm could be extended to patient populations.